An anchoring system within the sense of the present invention is used in formwork engineering when concreting reinforced concrete structures in order to install wall formworks. A wall formwork comprises a formwork facing on the front and elements supporting the formwork facing on the back, such as longitudinal beams, crossbars and frames. In the erected state of a wall formwork, a longitudinal beam extends in the vertical direction and a crossbar in the horizontal direction.
The two sides of a wall to be concreted are delimited by wall formworks. With its formwork facing, the front of each wall formwork in that case adjoins the concrete. Wall formworks facing each other are generally retained by a plurality of anchoring systems. The anchoring rods are pushed through openings in the wall formworks and attached at their ends by means of locking devices to the elements supporting the respective formwork facing in such a way that at least the tensile force acting upon the anchoring rods during concreting is absorbed. These openings that pass through the wall formworks are also referred to as anchoring rod bores.
Formwork engineering differentiates between a holding formwork and a closing formwork. A holding formwork is a wall formwork which is erected first. Subsequent thereto, the closing formwork is erected opposite from the holding formwork. The holding formwork and the closing formwork are connected to each other during assembly by means of one or more anchoring systems. Concrete is poured into the intermediate space between the holding formwork and the closing formwork. The hardening of the concrete creates a wall.
Usually, one or both ends of an anchoring rod comprise a threaded portion onto which nuts are screwed as anchor fixation members. The middle region of such an anchoring rod, to which concrete can adjoin during concreting, advantageously either has a smooth surface or is enveloped at least during concreting by a sleeve having a smooth surface. Otherwise, a threaded portion of an anchoring rod would be covered in concrete. In that case, the anchoring rod could no longer be pulled out of the hardened concrete without any trouble.
The maximum effective length of the anchoring rod, and thus the thickness of the wall to be concreted, is therefore determined, as a rule, by the length of the middle anchoring rod region with a smooth surface. At the same time, the pressure exerted by the liquid concrete on the formwork facing during concreting is diverted via the nuts onto the anchoring rods. In the process, the anchoring rods are subjected to tensile stress.
Spacers can be introduced between the formwork facings into the volume of the wall to be concreted, which are able to absorb compression forces arising during concreting, whereby it is ensured that these compression forces do not affect, i.e. reduce, the wall thickness in an undesirable manner. Alternatively or additionally, the locking devices can be attached to the wall formworks so that they are also able to absorb compression forces.
If the concrete that has been poured between two wall formworks has hardened, the anchoring rod is disengaged from a locking device and pulled out of the concrete wall. If necessary, the top side of a closing formwork is suspended from a hook of a crane prior to this, so that it does not fall over once all anchoring rods have been pulled out. Finally, the wall formworks are shifted in a suitable manner, for example by means of the crane, in order to produce a next wall or a next wall portion. If the wall formworks have been shifted, then the anchoring systems are again mounted or attached to the wall formworks.
From the printed publication WO 2008/089737 A1, an anchoring system is known with two locking devices and an anchoring rod for a wall formwork with a first and a second formwork element. On its two ends, the anchoring rod has one threaded portion, respectively, which are screwed into nut members of the locking devices. Each locking device comprises a dome plate that is attached to a rear side of a wall formwork by means of attachment means. Therefore, the anchoring system is capable of absorbing both tensile as well as compression forces of a wall formwork.
Unless otherwise stated below, the above-mentioned features, which are known from the prior art, can be combined, individually or in any combination, with the subject matter of the invention described below.